Belt tensioner

Abstract

A tensioning device for belts, chains and the like, particularly for toothed belts in the valve drive of internal combustion engines, the device comprising a support which can be fixed on the engine block and on which, firstly a lever carrying a pressure-contact roller is pivotably mounted, secondly, a tensioning element is arranged which presses against the lever via a piston and thirdly, a stop member is arranged which is displaceable parallel to its longitudinal axis from a mounting position into an operating position and in the mounting position blocks the stroke of the piston in an intermediate position by a stop surface and allows a free travel of the piston in the operating position, characterized in that the stop surface is formed by a lateral surface of the stop member which is parallel to the longitudinal axis of the stop member.

What we claim is: 
     
       1. A tensioning device for belts, chains and the like, particularly for toothed belts in a valve drive of internal combustion engines, the device comprising a support which can be fixed on an engine block and on which, firstly a lever carrying a pressure-contact roller is pivotably mounted on an axis, secondly, a tensioning element is arranged which presses against the lever via a piston and thirdly, a stop member is arranged which is displaceable parallel to its longitudinal axis from a mounting position into an operating position and in the mounting position blocks the stroke of the piston in an intermediate position by means of a stop surface and allows a free travel of the piston in the operating position, characterized in that the stop surface is formed by a lateral surface of the stop member which is parallel to the longitudinal axis of the stop member. 
     
     
       2. A tensioning device of claim 1 wherein the stop surface in the operating position is situated outside the movement of the lever. 
     
     
       3. A tensioning device of claim 2 wherein the longitudinal axis of the stop member is parallel to the pivoting axis of the lever. 
     
     
       4. A tensioning device of claim 1 wherein the longitudinal axis of the stop member is parallel to the pivoting axis of the lever. 
     
     
       5. A tensioning device of claim 1 wherein the stop member is formed by a stop pin or a cylindrical tensioning sleeve guided in frictional engagement in a bore of the support. 
     
     
       6. A tensioning device of claim 1 wherein the stop member in the mounting position extends in the direction of movement of the piston. 
     
     
       7. A tensioning of claim 6 wherein a flange of a tappet bears against the lever, one end of the tappet contacting the piston of the tensioning element and the other end, in the mounting position, contacting the stop surface of the stop member. 
     
     
       8. A tensioning device of claim 1 wherein the stop member and/or the piston engages an arm of the lever which is shorter than the lever arm on which the pressure-contact roller is mounted. 
     
     
       9. A tensioning device of claim 1 wherein the tensioning element is arranged in a housing made in one piece with the mounting location of the stop member on the support.